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. Author manuscript; available in PMC: 2010 Jun 14.
Published in final edited form as: Nat Struct Mol Biol. 2008 Apr 6;15(5):485–493. doi: 10.1038/nsmb.1412

Figure 4.

Figure 4

γ-domains are modular and can be switched between species to confer altered DNA sequence specificities. (a) Schematic depicting the architecture of the SpoIIIE-SK chimera containing the γ-domain of FtsK (dark red) fused to the motor domain of SpoIIIE (light red). (b) Representative trace of SpoIIIEC-SK chimera-induced changes in DNA extension versus time in the magnetic tweezers on a DNA substrate containing a triple repeat of KOPS (3 × SRS1) at the test location (black line). (c) SpoIIIEC-SK chimera DNA triplex displacement reactions on substrates containing either a triple KOPS sequence in permissive (green circles) or nonpermissive (red squares) orientations. Error bars indicate s.d. Data were normalized for the initial percentage of free triplex and fit to an exponential function. Ratio of displacement on permissive versus nonpermissive substrates is 1.8 ± 0.25. (d) Log of heat-resistant spore titers for wild-type SpoIIIE★ (orange), SpoIIIE★-Δγ (green) and SpoIIIE★-SK chimera (red) strains. Error bars indicate s.d. (e) Normalized DNA fluorescence intensity traces of individual SpoIIIE★-SK cells (different colors shown). Velocities of DNA translocation in vivo were 520 ± 100 bp s−1 (n = 16), similar to those of SpoIIIE★.